The aims of the project continue to focus on mechanisms involved in neurotransmitter release from synaptic vesicles. The specific aims are a) to characterize further the ATPase responsible for neurotransmitter by examining its factor requirements and physical characteristics; b) to elucidate the possible role of Ca 2ion in coupling excitation to transmitter release; c) to elucidate the nature of the interaction between the pre-synaptic membrane and synaptic vesicles required for transmitter release; d) to conduct biochemical analysis on the synaptic junction complex and to examine their binding characteristics for various neurotransmitter systems. In an effort to understand the mechanism of neurotransmitter release, the uptake, and release of 3H-dopamine will be examined in plain synaptic vesicles particularly with regard to the role of the synaptic membranes. It is generally accepted that catecholamines are released from synaptic vesicles directly into the extracellular space without first being released into the cytosol of the nerve endings. Another study will deal with the uptake of 3H-dopamine by synaptic vesicles. The addition of Mg 2ion and ATP increased the uptake 16-fold over the control, whereas the separate addition of the agents produced only a 2.5-fold increase. GTP was as effective as ATP while other nucleotides were ineffective. BIBLIOGRAPHIC REFERENCES: Ryo Tanaka, Hisateru Asaga, and Minoru Takeda (1976) Uptake of (3H) dopamine by plain synaptic vesicles, Transactions Amer. Soc. Neurochem. 6, 63. J.F. Goodrum, H.B. Bosmann, and Ryo Tanaka (1976) Glycoprotein: galactosyl transferase in synaptic junction complexes isolated from rat forebrain, Abstract of 1976 Meeting of Amer. Soc. Neuroscience.